i have a non power steering car and the steering wheel tightens pretty hard sporadically

I have a Suzuki esteem here in India with non power steering. the wheel tightens every now and then. i have the steering box replaced and have also replaced the shock absorbers. every 1000 kms, the steering tightens real bad and even at 100 plus speed its hard to move. and then it automatically loosens up and acts perfectly fine. the issue has been there on and off for a few months and the mechanic suspects it to be the Shock absorber bearing problem. please advise as almost everytime i have taken it to the mechanic it has been smooth and i suspect they may not be able to find the actual problem